The present invention relates to a tire and rim assembly for All Terrain Vehicles (ATV), in which the tire is prevented from slipped out from the rim even if the internal air is released by puncture or the like during running, and which is able to run under such a deflated condition.
In conventional pneumatic tires, the means of retaining the tire on a wheel rim is the internal air pressure, which passes the tire beads to the bead seats and flanges of the wheel rim. Accordingly, when the air pressure is decreased, the retention force is inevitably lowered.
Under such condition that the internal air pressure is rapidly decreased by puncture or the like, if a lateral force, for example that due to a sharp handling operation of the vehicle to avoid a possible accident, acts on the tire, it is transferred to the beads from the tread through the tire sidewalls and lifts the toe of one bead and the heel of another bead. As a result, the frictional force therebetween will be decreased, which leads to the bead slipping out from the bead seat and falling into the rim well for the tire mounting work. Such a dislocation of the tire leads not only to a lack of maneuverability but also to a dangerous situation wherein the tire drops off from the wheel rim.
To solve the above-mentioned problems, there has been proposed a tire and wheel rim assembly, wherein each bead of the tire is provided with a radially inwardly protruding toe, and each bead seat of the wheel rim is provided with a groove with which the toe is engaged, and the diameter of the resultant protrusion between the groove and the well is not more than the rim diameter.
On the other hand, pneumatic tires for ATV are used at a very low internal air pressure to increase its ground contacting area and to absorb shocks from the ground, and further the ATV tires are used in a very rough manner under high speed. Therefore, the sidewalls of the ATV tire is always subjected to side force, and the ATV tires are exposed to the danger of tire dislocation more than other kinds of tires not only in the abnormal condition in which the tire is punctured but also the normal operating conditions. Therefore, the above-mentioned system is insufficient for such a ATV tire.
Furthermore, the ATV tires are generally for sports use. It is therefore, desirable to reduce the tire weight to maintain good maneuverability.